1. Field of the Invention
This invention relates to a chip removing apparatus for a machine tool such as a wood working machine wherein chips produced by cutting by means of a tool attached to a lower portion of a working head are sucked upwardly to remove them.
2. Description of the Related Art
Conventionally, various chip removing apparatus are known, and an exemplary one of such conventional chip removing apparatus is shown in FIG. 5. Referring to FIG. 5, a working head 2 is mounted for upward and downward movement on a cross rail or column 1 of a machine tool. The working head 2 includes a motor 4 disposed in an inverted posture in a casing 3 having a tubular configuration. A tool chuck 5 is connected to a rotary shaft of the motor 4 and extends downwardly from a central portion of the bottom of the casing 3 so that a tool 6 such as an end mill or a drill is removably attached to the working head 2 by means of the tool chuck 5. A chip sucking passage 7 is defined between the casing 3 and the motor 4 and extends in the upward and downward direction through the working head 2. The chip sucking passage 7 passes a plurality of locations on an outer periphery of the motor 4 from a lower portion of the casing 3 and gathers together at a top portion of the casing 3. The chip sucking passage 7 is in communication with a suction duct not shown by way of a hose 8 connected to the top end of the casing 3.
A dust collection cover 9 formed cylindrically from a light alloy material, is fitted downwardly on and fixed to an outer periphery of a lower portion of the casing 3. A flexible annular skirt member 10 in the form of a brush extends downwardly from a lower circumferential edge of the dust collection cover 9 such that it surrounds outer peripheries of the tool chuck 5 and the tool 6 fastened to the tool chuck 5. In order to removably mount the dust collection cover 9 on the casing 3, rack-like teeth 11 are formed on the outer periphery of a lower portion of the casing 3, and a locking pawl 12 is mounted for pivotal motion on an inner face of a side portion of the dust collection cover 9. The locking pawl 12 is normally biased in a direction by a spring 14 so that it may be normally engaged with the teeth 11 on the casing 3.
The conventional chip removing apparatus, however, is disadvantageous in that, since chips collected in the dust collection cover 9 are sucked into the chip sucking passage 7 only by an air sucking force from the chip sucking passage 7, chips collected are not driven readily by air flows flowing upwardly in the dust collection cover 9 and cannot be removed smoothly. In particular, chips produced upon working by the tool 6 which rotates at a high speed are scattered radially outwardly by a strong centrifugal force, and consequently, the chips are not readily moved upwardly, that is, toward the chip sucking passage 7.